Effect of grading and lime content on HMA stripping using statistical methodology

Response surface methodology was employed to evaluate the effect of lime content and grading on the dry and saturated indirect tensile strength as well as Tensile Strength Ratio of hot mix asphalt. The statistical significance of linear, quadratic and interactive terms of these factors were examined and second order polynomial models were successfully fitted to the experiment data. It was shown that maximum Tensile Strength Ratio was achieved at 1% lime content and with grading containing most coarse aggregate. It was further concluded that decreasing the aggregate size and increase in mastic asphalt would increase the stripping potential of hot mixes asphalt.

► Based on statistical analysis, both linear terms of grading and lime content as well as interaction between them are significant in Tensile Strength Ratio of the hot mix asphalt with dense grading aggregate.
► The results also indicated that in the hot mix asphalt with dense grading aggregate, an increase in the amount of mastic asphalt makes it more prone to stripping.
► Based on our results if the fine grain content of a mixture increases, more lime is required to prevent or/and control the stripping events.